Apparatus for photo-telephones and the like

ABSTRACT

442,228. Photophones. ZEISS, C., [Firm of], Carl-Zeiss-Strasse. Jena, Germany. Aug. 4, 1934, No. 22780. Convention date, Aug. 17, 1933. [Class 40 (v)] Relates to a photophone in which the pencil of light for the transmission of sound is modulated by a body that moves relatively to a totally reflecting surface and is rigidly connected to a part influenced by electromagnetic or electrostatic means. According. to the invention, the body and the electrically influenced part are mounted on the body containing the totally reflecting surface. As shown in Fig. 1, light from a source b passes through a condenser a to a rectangular prism c by which it is reflected through an objective d. A glass plate e lies against the surface c&lt;1&gt; of the prism and is mounted in an armature f, Figs. 2 and 3, which is pivoted at f&lt;1&gt;, f&lt;2&gt; on the surface c&lt;1&gt;. A tongue cut out from the armature is pressed against the surface cl by an adjusting screw h&lt;1&gt; carried by a bar h fixed to the legs of a horseshoe magnet l which holds the prism c and is supported by the housing m. An elastic arm i also presses against the armature near its axis of oscillation, the arm being pivoted on a bolt i&lt;1&gt; on the magnet l and actuated by a two-armed lever j pivoted at j&lt;1&gt; on the housing m so as to adjust the distance of the plate e from the surface c&lt;1&gt; or the pressure of the plate against this surface. The magnet l carries cores k located on the side of the armature facing the prism, speech currents passing through the windings surrounding these cores causing the armature f and plate e to oscillate thereby varying the pressure with which the plate e lies against the surface c&lt;1&gt; so as to control the amount of light which is reflected through the objective d. Flutes may be provided either on the surface c&lt;1&gt; or on the surface of the plate e co-operating therewith.

7 Aug. 6, 1935. R. MECHAU ETAL 2,010,313

' APPARATUS FOR PHOTO TELEPHONES AND THE LIKE Filed Aug. 11, 1934 Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE v z,o1o.s1z APPARATUS FOR rno'ro-mmrnomzs sun THE LIKE Application August 11. 1934, Serial No. 739.382

Germany August 17, 1933 6 Claims. (Cl. 88-61) An application has been flled in Germany, August 1'7, 1933.

The present invention concerns an apparatus for photo-telephones and the like, in which the pencil of light for the transmission of sound is modulated by a body that moves relatively to a totally reflecting surface and is rigidly connected to an electrically influenced part. The electric influence may be for instance electromagnetic or electrostatic. The movement of the said body relative to the reflecting surface is to effect a more or less pronounced influence upon the quantity of reflected light raysl This movement isv generally at right angles to the reflecting surface and covers so short distances as correspond to wave-lengths of light. These apparatus are therefore very sensitive as regards such changes in the position of the said body as are unfortunately caused by influences of temperature and the like, the consequence being the necessity of readjustments of the apparatus even when this apparatus is in operation.

According to the invention, the electrically influenced part of the apparatus, for instance the armature of the electromagnet when the influence is electromagnetic, and the body effecting the modulation of the pencil of light are placed on the body containing the totally reflecting surface, and conveniently on the said reflecting surface itself. Not only is there attained in this manner that all moving parts occupy the least possible space, as a consequence of which undesired intermediate members between the electrically influenced part and the part changing the total reflection are avoided and the influence of changing temperatures is comparatively small, but a change of position of the moving parts as a whole relative to the reflecting surface is avoided.

The moving body effecting the modulations of the pencil of light rests conveniently against two points of the reflecting surface which determine an axis about which the body may oscillate. In this manner there is maintained the parallelity of the optically effective surface of the moving b'ody relative to the reflecting surface, which is of importance if the apparatus is to work correctly.

The optically effective surface of the moving body or the effective part of the totally reflecting surface is conveniently provided with flutes, flutes having proved to prevent an undesired adhesion of the moying body to the reflecting surface.

The accompanying drawing illustrates a constructional example of an apparatus according to the invention. Figure 1 shows schematically a top of view of the optical system of the apparatus. Figures 2 and 3 represent the apparatus in ,a horizontal anda vertical partial section, respectively. Figures 4, 5 and 6 illustrate views of single parts, Figure 5 being reproduced on an enlarged s'cale.

The optical system of the apparatus consists of a condenser a, which converges the rays of a source of light b, a rectangular prism c and an objective d. A glass plate e lies against, and is displaceable at right angles to, the surface c of the prism c. That surface of the glass plate e which faces the prism c is roughened by flutes e (Figure 5). As is shown by Figures 2 and 3, the plate e is mounted in a plate I of larger dimensions. This plate I is of iron, and the plate e protrudes therefrom to a slight extent. That surface of the plate I which faces the prism c has two parts f and I that protrude from the said surface. These two parts, by means of which the plate I lies against the prism 0, determine an axis of oscillation X--X (Figure 4) of the plate I. By means of three cuttings I I and f the plate I is provided with an elastic blade 0. Above the prism c and the plate I is a piece h in which is disposed an adjusting screw he that presses against the blade 9. An elastic arm i which is adjustable about a bolt 1' by means of a twoarmed lever 1 adjustable about a bolt ii presses against the plate near the axis of oscillation of this plate. The arm i and the screw h} adjust the desired magnitude of the distance of the glass plate e from the surface 0 or the pressure of-the plate e against the said surface by changing through the agency of the lever 7' the distance of the place at which the arm 2' lies against the plate from the axis X-X. At the prism side of the plate I are provided magnets k. The plate I thus represents the armature of these magnets and substitutes the diaphragm which has been in use so far and which has been mounted independently of the prism c.

Instead of roughening by flutes the surface of the plate a, a corresponding part of the surface 0 of the prism 0 can be roughened for instance by flutes c (Figure 6). There can be roughened as well both the plate 2 and the surface c When a current modulated by the human voice is made'to flow throughthe magnets k, the plate I and the glass body 0 oscillate about the axis X-X, and the pressure with which the body e lies against the surface c of the prism c is intensifled or weakened accordingly. According to the oscillations of the body e, the light emanating from the source of light 17 and striking the surface 0 is reflected by the surface 0 more or less on account of the change of the capacity of reflection of the surface 0 at the place at which this surface is in contact with the glass body e, the said change of capacity being due to the change of pressure, and the pencil of light leaving the objective d is modulated in the rhythm of the current in the magnet k.

We claim:

1. An apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being so disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection, a member provided near, and movable transversely to, the said body and adapted to change the magnitude of reflection of this surface for the pencil of light by moving and touching the reflecting surface in that part at which the pencil of light strikes the surface, an electric device influenced by the changes of the electric current and influencing the position of the said member, this member being movably mounted direct on the body having the reflecting surface.

2. An apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being so disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection,-a member provided near, and movable transversely to, the said body andadapted to change the magnitude of reflection of this surface for the pencil of light by-moving and touching the reflecting surface in that part at which the pencil of lightstrikes the surface, an electromagnetic device influenced by the changes of the electric current and influencing the position of the said member, this member being movably mounted direct on the body having the reflecting surface.

3. An apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being so-disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection, a member provided near, and movable transversely to, the said body, an electric device influenced by the changes of the electric current, the said member consisting of two parts, the one of these parts being adapted to change the magnitude of reflection of the reflecting surface for the pencil of light in that part at which the pencil of light strikes the reflecting surface, the other part being influenced by the said electric part and movably mounted on the reflecting surface of the said transparent body.

4. An apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being so disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection, a member provided near, and movable transversely to, the said body and adapted to change the magnitude of reflection of this surface for the pencil of light by moving and touching the reflecting surface in that part at which the pencil of light strikes the surface, an electric device influenced by the changes of the' electric current, the said member lying at two points on the reflecting surface of the transpar-t ent body and being oscillated by the said electric device, the two said points determining an axis of oscillation of the member.

5. An-apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being -so disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection, a member provided near, and movable transversely to, the said body and adapted to change the magnitude of reflection of this surface for the pencil of light by moving and touching the reflecting surface in that part at which the pencil of light strikes the surface, an electric device influenced by the changes of the electric current and influencing the position of the said member, this member being movably mounted direct on the body having the reflecting surface, those surfaces of the said transparent body and the said member which face each other being provided with flutes.

' 6. An apparatus for photo-telephones and the like, for modulating changes of an electric current to changes of a pencil of light, having a transparent body provided with a reflecting surface, this body being so disposed that the said pencil of light traverses the said body and strikes the reflecting body at an angle causing total reflection, a member provided near, and movable transversely to, the said body and adapted to change the magnitude of reflection of this surface for the pencil of light by moving and touching the reflecting surface in that part at which the pencil of light strikes, the surface, an electric device influenced by the changes of the electric current and influencing the position of the said member, this member being movably mounted direct on thebody having the reflecting surface, that superflcial part of the said member which is made to touch the transparent body being provided with flutes.

ROBERT MECHAU.

HUGO EISENHUT.

PAUL REINSCH. 

